[clang-format] BeforeHash added to IndentPPDirectives

Summary:
The option BeforeHash added to IndentPPDirectives.
Fixes Bug 36019. https://bugs.llvm.org/show_bug.cgi?id=36019

Reviewers: djasper, klimek, krasimir, sammccall, mprobst, Nicola, MyDeveloperDay

Reviewed By: klimek, MyDeveloperDay

Subscribers: kadircet, MyDeveloperDay, mnussbaum, geleji, ufna, cfe-commits

Patch by to-mix.

Differential Revision: https://reviews.llvm.org/D52150

llvm-svn: 356613